Effects of dose and duration of continuous GnRH-agonist treatment on induction of estrus in beagle dogs: Competing and concurrent up-regulation and down-regulation of LH release

Concannon, P W; Templé, Marie; Montañez, Alicia; Newton, L

doi:10.1016/j.theriogenology.2006.02.007

Cited by 25 publications

(29 citation statements)

References 3 publications

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“…There is indirect evidence for possible subliminal follicular waves that may not always overlap and for an increase in follicle quality during the late anoestrus increases in FSH. Using GnRH or GnRH‐agonist (GnRH‐A) to induce proestrus, some bitches fail to show proestrus in response to elevations in LH comparable with those seen in bitches that do respond (Concannon et al. 1989, 1993 1997, 2006a,b).…”

Section: Follicular Phasementioning

confidence: 99%

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Endocrinologic Control of Normal Canine Ovarian Function

Concannon

2009

Reprod Domestic Animals

125

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In dogs, the termination of the 3-10-month obligate anoestrus involves selection of a cohort of LH-sensitive follicles, presumably from a wave of dominant small antral follicles that would otherwise undergo atresia. The number and size of such follicles appears to increase, especially during the last 50 days of anoestrus when the already elevated concentrations of FSH become further elevated. The final selection and eventual terminal development of these follicles is caused by an increased frequency of high-amplitude LH pulses at the end of anoestrus. Concomitant increases in FSH are typically small or negligible. High concentrations of FSH in anoestrus are likely to be important in maintaining, if not stimulating, overlapping waves of dominant follicles throughout anoestrus, their expression of aromatase activity and basal oestradiol secretion sufficient to suppress LH by negative feedback. An attractive hypothesis is that late anoestrus increases in LH-stimulate synthesis of precursor androgen for already available FSH-dependent aromatase. After 7 or more days of elevated LH, and perhaps 2-5 days of semi-autonomous growth, with maximal oestradiol production reached, follicle capacity to further increase oestradiol becomes limited and excess progesterone becomes increasingly secreted. The pre-ovulatory LH surge and oestrus onset are then triggered - often synchronously and in concert with the terminal maturation of the follicles - by central effects of the large decrease in the oestrogen to progestin ratio. Follicular endocrine and paracrine events during and following the LH surge are likely similar to those reported for other species. The prolonged luteal phase lengths of 55-75 days in non-pregnant bitches bracket the 64 +/- 1 day in pregnancy and represent a genetically programmed luteal cell lifespan approximating gestation length as occurs in the luteal phase of hysterectomized animals of most polyoestrous artiodactyls and rodents. The 30-40-day slow regression after day 20 to 30 involves periodic cell death, diminution in cell size, low levels of apoptosis and minimal or modest involvement of endogenous prostaglandin F (PGF) production. The canine corpus luteum (CL) is dependent on both LH and prolactin as stimulating luteotrophins by day 15, and as required luteotrophins by days 20-25, if not earlier. Thereafter, both luteotrophins likely have cellular mechanisms of action similar to those reported for other species. Progesterone secretion during pregnancy is greatly enhanced by characteristic, and probably relaxin-stimulated, increases in prolactin concentration starting at or after day 25, and persisting to term. Near term, foetoplacental maturation results in the placental release of large, luteolytic amounts of PGF for 1-2 days pre-partum. Pre-partum luteolysis, like that induced by exogenous prostaglandin, likely involves a cascade enhanced by the removal of progesterone inhibition of PGF release and some degree of intra-luteal PGF synthesis. That a likely twofold or greater increase in progesterone ...

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Section: Follicular Phasementioning

confidence: 99%

“…1989, 1993 1997, 2006a,b). Results of Concannon et al. (2006a,b) suggested that 10% of anoestrous bitches may not have follicles able to respond to an LH stimulus that would otherwise induce a normal proestrus.…”

Section: Follicular Phasementioning

confidence: 99%

Endocrinologic Control of Normal Canine Ovarian Function

Concannon

2009

Reprod Domestic Animals

125

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“…In laying broiler breeder hens, increasing GnRH release can result in increased plasma LH and decreased FSH, and, in turn, increase the number of large preovulatory ovarian follicles [6]. Interestingly, an uninterrupted subcutaneous administration of a GnRH-agonist for 2 weeks also rapidly induced a normal estrus, with spontaneously occurring gonadotrophin surges and fertile ovulation [8,9]. GnRH treatment appears to be effective in stimulating a new ovulation/luteinisation of another follicle as it would in a non-cystic cow [18,24].…”

Section: Discussionmentioning

confidence: 99%

“…It has suggested that the use of GnRH agonists for the control of reproduction is of growing interest to increase the efficiency of reproductive performances in farm animals [25,41]. The use of GnRH and its analogue has been investigated in cows [59,61], mare [21], sheep and goats [26], fish [68], dogs [8], wildlife [2,5,42,54] and poultry [37,48]. Although parenteral administration of GnRH agonists practiced in flocks is difficult, GnRH agonists were primarily used by parenteral administration as discussed by [26,48].…”

Section: Introductionmentioning

confidence: 99%

Patterns of folliculogenesis in ducks following the administration of a gonadotropin-releasing hormone 1 (GnRH) analogue

Zoheir

Ahmed

2012

Journal of Genetic Engineering and Biotechnology

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The efficacy of synthetic gonadotrophin-releasing hormone (GnRH) analogue in improving the folliculogenesis of ducks has not been established. The aim of the study was to investigate the effect of oral administration of GnRH analogue as luteinizing hormone releasing hormone A 2 (LHRH-A 2 ) on expression of relevant genes, egg production, changes of hormone levels and an ovarian follicle development in ducks. Five hundred ducks at 220 days old were randomly allotted to five groups, where each bird received daily in food 0, 5, 10, 15, or 20 lg LHRH-A 2 for 60 days. In all treated groups, a non-significant increase in the level of GnRH receptor was noticed as compared to the corresponding control. Interestingly, the egg product in the 10 and 15 lg LHRH-A 2 groups was profoundly increased (P < 0.05) if compared to 0 and 5 lg LHRH-A 2 groups or control. A reduction in circulating prolactin (PRL) levels occurs concurrently with an increase in progesterone (P 4 ) and estradiol (E 2 ) particularly in 5, 10 and 15 lg LHRH-A 2 groups. Maximal apoptotic percentage for the granulosa cells was obtained in 20 lg LHRH-A 2 group as compared to control or 5, 10 and 15 lg treatment groups. Finally, these data suggest that the oral administration of 10 and 15 lg LHRH-A 2 may induce ovarian cycle and play vital gonadotrope role during the folliculogenesis process in ducks. This study also demonstrated a need to concentrate further research on the potential effect of GnRH during the early period to improve the reproductive performance.

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“…Köpeklerde fertil bir östrus uyarmak amacıyla bir GnRH agonisti olan lutrelinin en uygun dozunu belirlemek için yapılan bir araştırmada 0,6 µg/ kg dozda 12 günlük uygulamanın % 92 oranında gebelik ile sonuçlandığı bildirilmiş-tir. Araştırmacılar düşük dozların yetersiz uyarım yaparken yüksek dozların ise reseptör down-regülasyonu sonucunda istenilen oranda fertil östruslar oluşturmadığını bildirmişlerdir (29).…”

Section: Gnrh Agonistlerinin öStrus Uyarma Amacıyla Kullanımıunclassified

Di̇şi̇ Köpek Ve Kedi̇lerde Üremeni̇n Kontrolünde GNRH Agoni̇stleri̇

Çetin¹,

Koçak

2017

Mehmet Akif Ersoy Üniversitesi Veteriner Fakültesi Dergisi

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ÖZETKedi ve köpekler ev veya bahçe içlerinde bakıldıklarından östrus sırasındaki davranışları sorun olabilmektedir. Bir batında fazla sayıda yavru yapabilmeleri, gebelik ve doğum sırasında karşılaşılan sorunlar nedeniyle çoğunlukla gebe kalmaları istenmemektedir. Uzun zamandır kedi ve köpek gibi ev hayvanlarında cerrahi kısırlaştırma güvenilir ve kalıcı tek kontrasepsiyon yöntemi olarak kullanılmaktadır. Ancak bu yöntemin geri dönüşümsüz olması ve cerrahi müdahale gerektirmesi önemli bir dezavantajdır. Bu derlemede köpek ve kedide üremenin denetlenmesinde yeni bir seçenek olarak kullanılan gonadotropinreleasing hormon (GnRH) agonistleri hakkında bilgi sunulacaktır. CONTROL OF REPRODUCTION WITH GNRH AGONISTS IN BITCH AND QUEENS ABSTRACTThe behavior of female dog and cat may be a problem when they are live inside of house or home garden. The owners of bitch and queen are generally unwilling to reproduction because of higher litter size in one whelping, risks of pregnancy and parturition. Neutering has been widely used in the sterilization of dogs and cats for a long time. However, surgical spaying procedure has important advantages like surgical risks and irreversibility. In this review, we aimed to present an information about new alternative control of reproduction in bitch and queen with GnRH agonists.

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Effects of dose and duration of continuous GnRH-agonist treatment on induction of estrus in beagle dogs: Competing and concurrent up-regulation and down-regulation of LH release

Cited by 25 publications

References 3 publications

Endocrinologic Control of Normal Canine Ovarian Function

Endocrinologic Control of Normal Canine Ovarian Function

Patterns of folliculogenesis in ducks following the administration of a gonadotropin-releasing hormone 1 (GnRH) analogue

Di̇şi̇ Köpek Ve Kedi̇lerde Üremeni̇n Kontrolünde GNRH Agoni̇stleri̇

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